mat-clim-indices

This repo is a collection of Climate indices in MATLAB.

Information

The functions takes a data structure with the variables as fields. The variables array can be of dimensions 1, 2 or 3.

The data struct is as follows.

data.tasmin % Daily minimum temperature
data.tasmax % Daily maximum temperature
data.pr % Daily precipitation accumulation
data.tas % Daily mean temperature
data.dates % Dates vector

A time vector of size MxN is also necessary in the data struct, where M is the number of timesteps and N has at least a length of 3 (year, month, day). This can be created by the MATLAB function datevec.

Some functions needs other argument, such as the variable field. For example, tas, pr, tasmax, tasmin is needed for functions that calculate annual means, max and minium (i.e. annualmean, annualmin, annualmax).

N.B. It is not necessary to have all variables (e.g. .tasmin, .tasmax, .pr and .tas) in the data struct if the called functions does not need it. However, the .dates field is necessary.

Functions

The functions returns a struct.

indicator.data % Data array
indicator.dates % Date array
indicator.units % Unit
indicator.title % Title (for figure re-use)

Annual mean

indicator = annualmean(data, var::String)

Defn. Returns the annual mean values of variable 'var'.

Annual maximum

indicator = annualmax(data, var::String)

Defn. Returns the annual maximum values of variable 'var'.

Annual minimum

indicator = annualmin(data, var::String)

Defn. Returns the annual minimum values of variable 'var'.

Annual sum

indicator = annualsum(data, var::String)

Defn. Returns the annual summation of variable 'var'.

December-January-February sum

indicator = djfsum(data, var::String)

Defn. Returns the seasonal summation of variable 'var' over December, January and February.

June-July-August sum

indicator = jjasum(data, var::String)

Defn. Returns the seasonal summation of variable 'var' over June, July and August.

Growing season (length, start date, end date)

indicator = growseasonlength(data, code::Int)

Defn. Returns the length of the growing season. Needs variable 'tas' in data struct.
Code = 1 return the start date of the growing season (julian day)
Code = 2 return the end date of the growing season (julian day)
Code = 3 return the length of the growing season (days)

Mean precipitation during the growing season

indicator = pr_growseason_mean(data)

Defn. Mean precipitation during the growing season. Needs variables 'pr' and 'tas' in data struct.

Precipitation during the growing season

indicator = pr_growseason(data)

Defn. Precipitation total during the growing season. Needs variables 'pr' and 'tas' in data struct.

Annual frequency over a threshold

indicator = thresover(data, var, thres::Int/Float)

Defn. Returns the frequency of tasmax over a custom threshold 'thres'. Needs variables 'tasmax' data struct.

Unités thermique du maïs (Corn Heat Unit)

indicator = utm(data)

Defn. Returns the value of 'Unités thermiques maïs'.

Degree days during growing season

indicator = grow_dd(data, thres::Float)

Defn. Returns the growing degree days, as defined by the cumulative temperature over the threshold 'thres'.

Last spring frost

indicator = lastspringfrost(data, thres::Float)

Defn. Returns the julian day of the last spring frost with respect to threshold 'thres' (usually 0 Celsius).

Length of frost free season

indicator = cnfd(data)

Defn. Returns the length of the frost-free season. Hardcoded to lastspringfrost of 0 Celsius and firstfallfrost of -2 Celsius.

N.B. cnfd stands for 'consecutive no frost days'.

First fall frost

indicator = firstfallfrost(data, thres::Float)

Defn. Returns the julian day of the first spring frost with respect to threshold 'thres' (usually -2 Celsius)